Thanks Rainer.May I ask what is the difference between symmetric and asymmetric lenses? I googled but didn't get satisfied results...

Quote from: rainer_v

in any case the results with unsymmetric shift lenses as nikon/canon/schneider/contax/olympus arent comparable with symmetric lenses with large image circle as used on the alpas/cambos/artecs or on 4x5".

What is the difference between symmetric and asymmetric lenses? I googled but didn't get satisfied results...

with symmetric lenses the rear elements are exactly the same than the front elements, but in case of wide angles the lens has to come very close to the capture unit ( as film or digi back ), therefor symmetric wides cant be used with mirror boxes in between. distortion can be removed completely because the rear element distorts in the same way ( but in the opposite direction ) than the front elements. so theses two distortions eliminate themselves, tieory to 100% but of course there are production tolerances between the single lense elements. ( exist the same in the audio world with symmetric cables ...).

unsymmetric lenses can be mounted more far away ( in case of wides ) to reach this the lrear element of the lens has to be a different constrcution than the front element, in ths way it projects the image farer away ( or closer in case of tele lenses). because this two basic lens elements are now different their distortion is also different and the optical elimination of the distortions is not working anymore, at least not to 100%. results are visible distortions.

Rainer:Thanks so much for your effort to clarify the concept! I remember now the biogon 38mm on hassie swc is a typical symmetric lens...And it seems that it's a cost for slr cameras not to have great WA lenses like biogon..

Regards,Dustblue

Quote from: rainer_v

with symmetric lenses the rear elements are exactly the same than the front elements, but in case of wide angles the lens has to come very close to the capture unit ( as film or digi back ), therefor symmetric wides cant be used with mirror boxes in between. distortion can be removed completely because the rear element distorts in the same way ( but in the opposite direction ) than the front elements. so theses two distortions eliminate themselves, tieory to 100% but of course there are production tolerances between the single lense elements. ( exist the same in the audio world with symmetric cables ...).

unsymmetric lenses can be mounted more far away ( in case of wides ) to reach this the lrear element of the lens has to be a different constrcution than the front element, in ths way it projects the image farer away ( or closer in case of tele lenses). because this two basic lens elements are now different their distortion is also different and the optical elimination of the distortions is not working anymore, at least not to 100%. results are visible distortions.

The bowing effects on Graham's pano seem to be caused by the projection method for stitching. Using rectilinear projection won't cause the bowing effect, it's the cylindrical and equirectangular projection make it bowing.

While the problem is, when the field of view is too big, like 180 degree which Rainer has mentioned, we won't use rectilinear projection, otherwise we'll have horrible distorted big edges. While in the same time, we don't have such a WA lens which FoV is bigger than 180 degree. So sometimes the bowing effect is just inevitable, which is why I'm so frustrated with one of the image I post upstairs...

And I think it's why Rainer said big FoV shot is not easy.

I try to make a screen shot of the ptgui software stitching big FoV pano to make it clear, but ptgui doesn't work on my pc right now...I should fix it later, sorry for that.

Regards,Dustblue

Quote from: rethmeier

I would like to make a comment on Graham's image.The only reason for the bowing of some of the buildings is that the image was done with a pano-stitch.

If the same image was done as a single shot with a shift lens,you wouldn't have the bowing or curving.The lines would all be straight.

I like it a lot.Is this morning or evening sun? Looks like morning... And - if I may ask - did you use a reflector? Anyway, the structures are well worked out so it has a strong graphical impact but at the same time a great deapth. Looks "easy" but one have to see it that way first.Aber ganz oben rechts und ganz unten links, da strahlt was in die Ecken :-)What does "Minas" stands for in your serial?

As so much architecture is posted now I'll maybe throw one in, too.I'm honestly not sure about this one. On the one side I like it one the other hand the forground is maybe ...a bit twitchy?[attachment=9076:CF002230.jpg]edit: Cambo WRS, Digitar 47XL, P45; 2 captures stitched

I like it a lot.Is this morning or evening sun? Looks like morning... And - if I may ask - did you use a reflector? Anyway, the structures are well worked out so it has a strong graphical impact but at the same time a great deapth. Looks "easy" but one have to see it that way first.Aber ganz oben rechts und ganz unten links, da strahlt was in die Ecken :-)What does "Minas" stands for in your serial?

As so much architecture is posted now I'll maybe throw one in, too.I'm honestly not sure about this one. On the one side I like it one the other hand the forground is maybe ...a bit twitchy?[attachment=9076:CF002230.jpg]edit: Cambo WRS, Digitar 47XL, P45; 2 captures stitched

very nice shot. about the foreground i agree. maybe a little bit less space for it and less color would be more ?

"minas" is spanish for " (iron/copper/gold) mines". its evening sun, and .... yes , some vignetting is visible but will be worked out or cropped a little bit,- i will see.

I like the composition and colors alot. Maybe if added a bit of blur to the foreground to calm the weedy chaos? It seems to distract from the true subject.

Quote from: tho_mas

As so much architecture is posted now I'll maybe throw one in, too.I'm honestly not sure about this one. On the one side I like it one the other hand the forground is maybe ...a bit twitchy?[attachment=9076:CF002230.jpg]edit: Cambo WRS, Digitar 47XL, P45; 2 captures stitched